Add Opencode and Ollama modules; update configs

Enable Opencode and Ollama in home modules and import their Nix files.
Disable the deprecated system‑module opencode entries and remove it from
the
core packages list.
Add a new GitHub CLI module and a convenient `upf-gh` alias for flake
updates using a GitHub token.
Update the `stylix` configuration to include Opencode styling.
Refresh several flake.lock entries with newer revisions and hashes.

modules/core/packages/programs.nix

@@ -1,22 +1,30 @@
 {shell, ...}: {
   programs = {
     nano.enable = true;
+
     hyprland = {
       enable = true;
       withUWSM = false;
     };
+
     fish.enable =
       if shell == "fish"
       then true
       else false;
+
     dconf.enable = true;
+
     seahorse.enable = true;
+
     fuse.userAllowOther = true;
+
     mtr.enable = true;
+
     gnupg.agent = {
       enable = true;
       enableSSHSupport = true;
     };
+
     nix-ld = {
       enable = true;
       # libraries = with pkgs; [